One of New York’s two major suicide hot lines will go silent unless the city Health Department rescinds a $247,150 budget cut, alarmed officials warned yesterday.

“It’s a major mistake that will literally cost this city money, precious free resources and — most important — people’s lives,” Fiodhna O’Grady, director of operations for The Samaritans, testified at a City Council budget hearing.

The two-decade-old group handled 65,000 calls last year alone, O’Grady noted.

A spokesman for Mayor Bloomberg, Marc LaVorgna, countered that LifeNet, the other 24-hour hot line, could pick up the slack.

But officials at The Samaritans pointed out that they provide intensive counseling while LifeNet is an information-referral service.